Crawler

Abstract: A crawler block rubber pad for a crawler (10) which has an endless path of movement and which is used for a vehicle. Links (1) are axially supported and connected by pins (6) in an endless shape, and crawler blocks (2) are attached to outer surfaces of the links. In the crawler block rubber pad, a rubber pad (3) is formed integrally, by vulcanization and adhesion, to an outer side surface of a crawler block and to end portions of the crawler block as seen from a longitudinal direction of the links. Preferably, the rubber pad is vulcanized and adhered to both end portions of the crawler block in the longitudinal direction of the links. Even if a small stone or the like becomes caught in a space between crawler blocks which space widens when the crawler is trained around an idler of the like, because a thickness of rubber material is provided so as to be larger than a radius of a small stone, no unwanted force is applied to the pins and the links.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a rubber pad of crawler block for a crawler. Furthermore the invention relates to a crawler comprising links connected together by connecting members to form an endless shape such that the links can be assembled onto a drive mechanism of a machine such as a machine used for construction, a machine used for civil engineering or the like. Description of the Related Art When machines for construction or machines for civil engineering work travel on paved roads, the paved surface may be damaged. As a result, crawler blocks having rubber pads on the outer surfaces thereof have come into use in place of steel crawler blocks. Fig. 23 is a side view of a conventional crawler using crawler blocks having rubber pads. Fig. 24 is a side view of the crawler trained around a sprocket or an idler. In the drawings, 1 0 is a link, 2 0 is a crawler block, and 3 0 is a rubber pad vulcanized and adhered to the outer surface of the crawler block 2 0 . The links 1 0 and the crawler block 2 0 are fixed by bolts 4 0 and nuts 5 0 . Adjacent links 1 0 , 1 0 are axially supported by pins 6 0 . The crawler is trained around unillustrated track rollers or sprockets or around idlers 7 0 which contact the upper surfaces of the links 1 0 so that the crawler rotates and travels. Further, when the crawler is trained around a sprocket or the idler 7 0 , as illustrated in Fig. 23, the line connecting the pins 6 0 , 6 0 of the crawler becomes a neutral line. The crawler rotates with the portions thereof at the inner side of this line narrowing, while the portions thereof at the outer peripheral side of the line widen. When the crawler is trained around the idler 7 0 or the like, the spaces (W 0 ) between outer peripheral sides of adjacent crawler blocks 2 0 , 2 0 become very large. Therefore, small stones, pieces of ore or the like may become caught in the spaces such that damage to the crawler blocks 2 0 and the rubber pads 3 0 is unavoidable. Further, crawler rubber shoes in which rubber is vulcanized and adhered to the ground-contacting surface thereof have by preference come into use. Fig. 25 is a ground-contacting surface side plan view illustrating an example of a crawler rubber shoe. Fig. 26 is a side view thereof, and Fig. 27 is a cross sectional view taken along line N-N of Fig. 25. In the conventional crawler rubber shoe, a metal crawler block 54 is attached by bolts 52 and nuts 53 to connection links 51 which form the crawler. Usually a grouser 55 is formed at the ground-contacting surface side of the metal crawler block 54, i.e., at the outer surface side of the crawler block 54. A rubber pad 56 is vulcanized and adhered so that the grouser 55 is covered. In the conventional crawler block rubber shoe described above, the rubber pad 56 is vulcanized and adhered to the outer side surface of the metal crawler block 54, and the top surface of the rubber pad 56 is a substantially flat surface. Depending on the case, the rubber pad 56 may be formed such that, as illustrated in Fig. 28, the center of the top surface thereof is flat, whereas the end portions thereof are formed to have smaller thicknesses. As a result, when a crawler using this crawler block rubber shoe is used as the traveling device of a machine, peeling of the rubber pad 56 from the metal crawler block 54 occurs easily. Further, the surface pressure on the central portion of the rubber pad 56, which supports the weight of the machine body, becomes much larger than the surface pressure on the end portions. As a result, defects in the rubber concentrate at the central portion where the surface pressure is high. Moreover, because the grouser 55 is formed at the outer surface side of the crawler block 54 in the longitudinal direction thereof, the thickness of the rubber with respect to the ground-contacting surface of the rubber pad 56 varies. As a result, the compressive strain on the rubber pad 56 varies at the respective portions thereof. The durability of the rubber therefore markedly deteriorates. When the crawler travels over small stones or the like, the crawler bends toward the inner side, i.e. , so-called "reverse bending" occurs at the ground-contacting regions of the crawler. In this case, the end portions of adjacent crawler blocks contact each other so that the reverse bending is stopped. However, usually, there is a large space between the crawler blocks, and even if reverse bending occurs, it is difficult for the end portions to contact each other. Accordingly, it is difficult to prevent reverse bending. The conventional crawler rubber pad covers the outer surface side of the crawler block and is vulcanized and adhered thereto. During manufacturing, the crawler block is set in a mold, and the remaining space in the mold is filled with rubber. The rubber which has been made fluid moves easily around not only the ground-contacting surface of the crawler block, but also to the inner side thereof. Track links are to be fixed to this crawler block, but because the inner surface of the crawler block and the inner surface of the rubber pad are in the same plane, the protruding of rubber at the inner surface side of the crawler block is quite incommodious, and the entire protruding rubber portion must be removed when the track links are to be attached. Namely, the protruding rubber which has circled around to the inner side of the crawler block is removed by a knife or by buff finishing. Such processes not only require labor, but also, the main rubber pad body is easily damaged in such processes. Accordingly, there is a need for improvement. A crawler with links connected to each other by a connecting member and comprising a crawler block is shown in GB 503,119. The crawler block has the form of a plate which is attached to the link by a nut and a bolt. A pad is vulcanised and adhered both on inner and outer surfaces of the plate. Furthermore, the pad abuts against a flange which is part of the link. Additionally, a housing is formed in the outer side surface of the pad such that the nut can be tightened. In EP 0 516 128 a shoe of a crawler belt or chain is shown including links connected by connector members. On each link a crawler block is attached on which the outer side surface a rubber pad is vulcanised and adhered. The peripheral portions of the pad are formed in a convex shape or have tapered side surfaces. SUMMARY OF THE INVENTION An object of the present invention is to prevent peeling of the crawler block rubber pad and to substantially uniformize the surface pressure applied to the rubber pad, so that defects in the rubber pad can be reduced. This object is solved by a rubber pad according to claim 1 as well as by a crawler according to claim 8. In the present application, the "inner side" of the crawler block or the rubber pad refers to the side of the crawler block or the rubber pad toward the sprocket or idler. The "outer side" of the crawler block or the rubber pad refers to the side of the crawler block or the rubber pad at the side opposite the sprocket or idler side. In a fourth aspect of the present invention each rubber pad has a portion that extends away from an outer perphery of a crawler block such that substantially no gap between adjacent rubber pads exists. Even if a small stone or the like becomes caught in the space between the crawler blocks which space widens when the crawler is trained around a sprocket or an idler, due to the compressive deformation of the rubber material at these portions, unwanted force is not applied to the pins and the links. It is optimal that the rubber pad, which is integral with the crawler block, is vulcanized and adhered. In particular, the rubber material is formed integral with the pad material at the end portions of the crawler block oriented in the longitudinal direction of the crawler. The rubber material can be formed at one of these end portions of the crawler block. However, it is good to form the rubber material at both ends. In particular, it is preferable from the standpoint of the durability of the rubber that the rubber material is provided substantially uniformly at both ends. The thickness, in the longitudinal direction of the crawler, of the rubber material formed at the end portions of the crawler block fills the space which opens when the crawler is trained around a sprocket or an idler. Further, in cases in which the rubber material not only is thick, but also, the thickness is greater than the space between adjacent crawler blocks when the crawler is disposed in the horizontal direction, unwanted force is not applied to the pins connecting the links. However, because the rubber materials are elastic, a permissible range for the thickness of the rubber material in the longitudinal direction of the crawler is about 5 to 10 mm greater than the space between adjacent crawler blocks, depending of course on the type of crawler. The durability of the pad crawler (a crawler in which pads are adhered to metal crawler blocks) is related to the thickness of the rubber pad. When a flat crawler block is used, the pad thickness is uniform, local abrasion and breaking are prevented, and durability improves. In the present invention, even if small stones or the like become caught in the spaces between the crawler blocks which spaces become wider when the crawler is trained around a sprocket or an idler, because the rubber materials at these portions compressively deform, unwanted force is not applied to the pins and the links. Accordingly, the durability of the crawler is improved. More concretely, the crawler block 2 may have the same dimension to the transverse ends thereof, as illustrated in Fig. 1. However, in the example of Fig. 1, the transverse end portions of the crawler block 2 are formed so as to have somewhat smaller widths. The rubber materials 3 1 , 3 2 , 3 3 , 3 4 are formed at the respective peripheral ends of the crawler block 2, and in the example, extend to the reverse surface side of the crawler block 2. Forming the rubber material 3 5 at the reverse surface side of the crawler block 2, i.e., at the link 1 side of the crawler block 2, prevents peeling of the rubber pad 3 from the crawler block 2. A further aspect of the present invention is a rubber pad a thickness (h 2 ) of a peripheral portion of said rubber pad along each longitudinal direction end and/or each transverse directional end of said crawler block which peripheral portion extends from a plane contacting said crawler block to an outer side surface of said rubber pad being greater than a thickness (h 1 ) of a central portion of said rubber pad, which central portion from the surface contacting said crawler block to the outer side surface of said rubber pad. In a preferred embodiment of the present invention, thicknesses of portions of four peripheral portions of said rubber pad, as seen from a direction orthogonal to the outer side surface of said crawler block, which portions are from the plane contacting said crawler block to the outer side surface of said rubber pad, are respectively greater than h 1 . In another embodiment of the present invention, the thicknesses of the portions of four peripheral portions of said rubber pad are respectively substantially 1 to 10 mm larger than h 1 , preferably h 1 is greater than or equal to 20 mm. In another embodiment of the present invention, h 2 is greater than or equal to 10 × (weight of machine body in tons) 0.5 mm. In a tenth aspect of the present invention, h 2 is greater than or equal to 20 mm and is greater than or equal to 10 × weight of machine body in tons) 0.5 mm. In the present invention, because the rubber pad extends to the inner side end portion of the crawler block. peeling of the rubber pad from the crawler block can be prevented. The surface configuration of the rubber pad formed at the ground-contacting surface of the crawler block is a specific configuration. Namely, the end portions of the rubber pad are formed so as to be more thick than the central portion. Due to the central portion of the rubber pad being recessed further than the peripheral portions, the thicknesses are set so as to allow for the ground-contacting surface of the rubber pad to be horizontal in a case in which the load of the machine body is applied to the rubber pad. In this way, the concentration of the load of the machine body on the rubber pad is dispersed. Defects in the rubber pad and the concentration of external damage can be prevented, and the life span of the entire rubber pad can be extended. In the present invention, an ordinary metal crawler block is used. However, depending on the case, a fiber-reinforced resin block, for example, may be used. The results of various experiments revealed that damage to the rubber pad could be made insignificant by restricting the thicknesses h 1 , h 2 of the rubber pad to specific ranges. The reason why h 1 is greater than or equal to 20 mm is that, if h 1 is too small, when the crawler travels over stones or the like, the rubber pad may be caught between the stone and the crawler block and may be easily damaged. On the other hand, if h 2 is set to greater than or equal to 10 × (machine body weight in tons) 0.5 mm, the thickness of the rubber generally contributes to the durability of the rubber pad, and as the rubber thickness increases, the durability improves. When the rubber pads were used in experiments with different machine bodies, it was found that h 2 was proportional to the square root of the weight of the machine body used in the experiment. On the basis of this discovery, the range of h 2 was restricted. It is preferable that h 2 also is greater than or equal to 20 mm for the same reasons as h 1 . In the present invention, the rubber pad is formed at the outer side surface and the inner side end surface of the crawler block at the crawler rubber pad. The four peripheral portions of the ground-contacting surface of the rubber pad are more thick than the central portion. In this way, peeling of the rubber pad from the crawler block can be prevented, and the load of the machine body can be applied uniformly to the rubber pad. Therefore, the life span of the rubber pad can be improved. In a fourteenth aspect of the present invention grooves are formed along a longitudinal direction of said crawler block in inner side surfaces of portions of said rubber pad which portions are in vicinities of the both end portions of said crawler block. The rubber pad which is formed integrally with the crawler block is formed by vulcanization and adhesion. In particular, the rubber pad is formed integrally at the end portions of the crawler block. When the crawler blocks are connected so as to form the crawler, the space between adjacent rubber pads is restricted to a particular range. Even if reverse bending occurs, adjacent rubber pads promptly contact each other so as to check the reverse bending. In accordance with the present invention, when the crawler is trained around an idler or the like, the opening between adjacent rubber pads is made smaller so that small stones or the like are seldom caught between the rubber pads, and the life span of the crawler can be extended. In a further aspect of the present invention regions of said crawler blocks to which said links are adjacent protrude and are exposed further inwardly than inner side surfaces of said rubber pads. In the present invention, the rubber pad, which protrudes toward the inner peripheral side of the crawler block, does not exist at the regions of connection between the crawler block and the track links. More specifically, the crawler block is set in a manufacturing mold such that the inner surface of the crawler block protrudes inwardly. The protruding rubber does not extend to the inner surface. In this way, the protruding rubber is not obstructive during the connecting of the crawler block and the track links. The present invention is commodious for the attaching of the crawler rubber pad and the track links. The crawler rubber pad and the track links can be attached even if the rubber pad flows to the inner peripheral side of the crawler block. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of a crawler using a crawler block rubber pad of the present invention. Fig. 2 is a side view illustrating a state in which the crawler illustrated in Fig. 3 is trained around an idler. Fig. 3 is a ground-contacting surface side plan view illustrating an embodiment of a crawler block rubber pad of the present invention. Fig. 4 is a cross sectional view taken along line D-D of the crawler block rubber pad of Fig. 3. Fig. 5 is a cross sectional view taken along line C-C of the crawler block rubber pad of Fig. 3. Fig. 6 is a view illustrating the state of a region in Fig. 5 when the crawler block rubber pad of the present invention is used. Fig. 7 is a cross sectional view taken along line D-D of Fig. 3 in a further embodiment of a crawler block rubber pad of the present invention. Fig. 8 is a cross sectional view, which is similar to Fig. 5, in a further embodiment of a crawler block rubber pad of the present invention. Fig. 9 is a ground-contacting surface side plan view of a further embodiment of a crawler block rubber pad of the present invention. Fig. 10 is a side view of the crawler block rubber pad of Fig. 9. Fig. 11 is a front view of the crawler block rubber pad of Fig. 9. Fig. 12 is a ground-contacting surface side plan view illustrating a first crawler block rubber pad of another embodiment of the present invention. Fig. 13 is a front view of the crawler block rubber pad of Fig. 12. Fig. 14 is a side view of the crawler block rubber pad of Fig. 12. Fig. 15 illustrates a crawler block rubber pad used in a crawler of an embodiment of the present invention. Fig. 16 is a side view of a crawler using the crawler block illustrated in Fig. 15. Fig. 17 is a plan view of a portion of an inner peripheral side of a crawler block rubber pad of another embodiment of the present invention. Fig. 18 is a plan view of a portion of an outer peripheral side of the crawler block rubber pad of another embodiment. Fig. 19 is a cross sectional view taken along line J-J of Fig. 17. Fig. 20 is a cross sectional view of a mold for forming the crawler block rubber pad. Fig. 21 is a graph illustrating the relationship between machine body weight and thickness of the rubber pad illustrating the durability of the crawler block rubber pad of the present invention. Fig. 22 is a graph illustrating the relationship between durability time and the F/P value of the crawler block rubber pad of the present invention. Fig. 23 is a side view of a crawler using crawler blocks equipped with conventional rubber pads. Fig. 24 is a side view illustrating a state in which the crawler of Fig. 23 is trained around an idler. Fig. 25 is a ground-contacting surface side plan view illustrating an example of a conventional crawler rubber pad. Fig. 26 is a side view illustrating the crawler rubber pad illustrated in Fig. 25. Fig. 27 is a cross sectional view taken along line N-N of the crawler rubber pad shown in Fig. 25. Fig. 28 is a cross sectional view similar to Fig. 27, illustrating another example of a conventional crawler rubber pad. Fig. 29A is a reverse surface side plan view of a rubber pad and a crawler block in which rubber has been removed from the surface of the crawler block to which surface links are attached. Fig. 29B is a reverse surface side plan view of a rubber pad and a crawler block in which rubber has been removed from the surface of the crawler block to which surface links are attached. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the crawler block rubber pad of the present invention will be described in detail with reference to the drawings. Fig. 1 is a side view of a crawler 10 using the crawler block rubber pad of the present invention. In the drawings, reference numeral 1 is a link, 2 is a crawler block, and 3 is a rubber pad. Bolts 4 are inserted from a central recess 3' of the rubber pad 3, and are screwed with nuts 5 so that the links 1 and the crawler block 2 are fixed integrally. The links 1, 1 are axially supported by pins 6 so as to form an endless structure. The rubber pad 3 covers the outer surface of the crawler block 2. Rubber materials 3 1 , 3 2 , which are portions of the rubber pad 3, are vulcanized and adhered integrally to end portions 2 1 , 2 2 of the crawler block 2 in the longitudinal direction of the crawler 10. In the present embodiment, the respective widths of the rubber materials 3 1 , 3 2 are equal. The crawler block 2 may have the same dimension to the transverse ends thereof. However, in the present embodiment, the transverse end portions of the crawler block 2 are formed so as to have somewhat smaller widths. The rubber materials 3 1 , 3 2 , 3 3 , 3 4 are formed at the respective peripheral ends of the crawler block 2, and in the present embodiment, extend to the reverse side of the crawler block 2. Forming the rubber material 3 5 at the reverse side of the crawler block 2, i.e., at the link 1 side of the crawler block 2, prevents peeling of the rubber pad 3 from the crawler block 2. As illustrated in Figs. 29A and 29B it is preferable that the links 1 are attached to the crawler block 2 after the rubber, which adhered to the surface of the crawler block 2 to which the links 1 are attached, has been removed. Due to the transverse end portions of the crawler block 2 being tapered as illustrated, the stresses on the rubber pad 3 can be made equal at the central portion and the end portions of the crawler block 2. The durability of the rubber pad 3 is substantially equal at the respective portions thereof, and the life span of the rubber pad 3 can be extended. These advantageous effects can be further promoted by narrowing the transverse end sides of the ground-contacting top surface of the rubber pad 3 to conform to the configuration of the crawler block 2. In particular, the tractive force on damp or wet ground can thereby be improved. The same effect can be achieved by forming the transverse end portions of the crawler block 2 as curved surfaces. As the curvature increases, the effect improves. Fig. 2 is a side view illustrating a state in which the crawler 10 is trained around an idler 7. As can be seen from Fig. 2, the opening W 1 between the rubber pads 3, 3 of the present invention which cover the crawler blocks 2 is quite small as compared with the opening W 0 when conventional crawler blocks 2 0 are trained, as illustrated in Fig. 24. It is preferable that the width of each of the rubber materials 3 1 , 3 2 is a width which eliminates as much as possible the space between the crawler blocks when the crawler 10 is trained around sprockets or the like. However, if the width of each rubber material 3 1 , 3 2 is made too large, unwanted force is applied to the pins and the crawler blocks 2 when the crawler 10 is in a horizontal region. Accordingly, it is preferable that the widths of the rubber materials 3 1 , 3 2 of the rubber pad 3 are about 5 to 10 mm smaller than the space between adjacent crawler blocks 2, 2, i.e., the crawler block pitch, when the rubber pads 3 are disposed horizontally. In order to prevent so-called reverse bending, the crawler block width may be larger than the mounting pitch of the crawler block 2. However, in this case as well, the crawler block width should be no more than about 5 to 10 mm larger than the crawler block pitch. Further embodiments of the present invention will be described hereinafter with reference to the drawings. Members which are the same as those of the first through fourth embodiments are denoted by the same reference numerals, and description thereof is omitted. Fig. 3 is a ground-contacting surface side plan view illustrating a fifth embodiment of the crawler block rubber pad of the present invention. Fig. 4 is a cross sectional view taken along line D-D of Fig. 3, and Fig. 5 is a cross sectional view taken along line C-C of Fig. 3. In the drawings, reference numeral 1 is the link. A metal crawler block 12 is attached to the links 1 by the bolts 4 and the nuts 5. A rubber pad 13 is vulcanized and adhered on the outer side surface, i.e. , the ground-contacting surface side, to the inner side end surface of the metal crawler block 12. Holes 17 1 . 17 2 , in which the bolts 4 are inserted, are formed in the metal crawler block 12 and the rubber pad 13. The outer surfaces of the metal crawler blocks 12 in a plane parallel to the endless direction when the crawler block rubber pads are connected endlessly form a flat surface. In this way, the rubber pad 13 is vulcanized and adhered to the outer side surface of the metal crawler block 12, and a rubber material 13 1 extends to the inner side end surface of the metal crawler block 12. Therefore, peeling of the rubber pad 13 from the metal crawler block 12 can be deterred. The thickness of the central portion of the rubber pad 13 at a region along longitudinal (lengthwise) ends 12 2 , 12 3 of the metal crawler block 12 viewed from the transverse direction of the crawler is h 1 . The thickness h 1 is smaller than the thickness h 2 of the peripheral portions. The figures illustrate an example in which inclined surfaces 13 2 are provided from the central portion of the rubber pad to the peripheral portions. As a result, as illustrated in Fig. 6, when the crawler block rubber pads are connected to the links 1 and used, the rubber pads 13 elastically deform and protrude toward the outer sides, and the metal crawler block 12 bends due to the load applied thereto. As a result, even if load is applied to the machine body, because the rubber pad 13 is provided substantially uniformly on the entire surface of the metal crawler block 12, the surface pressure is substantially uniform and the strain on the rubber pad 13 does not concentrate at one portion. Fig. 7 is a cross sectional view along line D-D of Fig. 3, and illustrates another embodiment of the crawler block rubber pad of the present invention. In the present embodiment, the rubber pad 13 corresponding to ends 12 4 , 12 5 of the metal crawler block 12 forms tapered surfaces 13 3 , and the thickness h 2 is large. Fig. 8 is a cross sectional view which is similar to Fig. 5 and illustrates a further embodiment of the crawler block rubber pad of the present invention. In the present embodiment, stepped portions 13 4 are formed from the central portion of the rubber pad 13 to the peripheral portions such that the thickness h 2 of a region along the longitudinal ends 12 2 , 12 3 of the metal crawler block 12 is greater than the thickness h 1 of the central portion. Fig. 9 is a ground-contacting surface side plan view in the other embodiment of the crawler block rubber pad of the present invention. Fig. 10 is a side view thereof, and Fig. 21 is a front view thereof. In this crawler block rubber pad, because the thickness h 1 of the central portion of the rubber pad 13 is quite small, the rubber pad 13 is divided into rubber materials 13a, 13b at the left and the right in the longitudinal direction of the crawler block 12, and the rubber pads 13a, 13b are trapezoidal. Further, as both end portions of the rubber pads 13 become the longitudinal ends, they become inclined surfaces 13c, 13d which are cut out to a large degree. The relationship between the machine body weight and durability of the crawler block rubber pad having this configuration was determined by experimentation. It was found that durability is proportional to h 2 , that the rubber thickness (height) h 2 is substantially proportional to the square root of the machine body weight, and that durability is improved. The following dimensions provide crawler block rubber pads which are appropriate with respect to durability and the amount of consumed rubber: for a machine body weight of about 4 to 6 tons, h 1 is 20 mm and h 2 is 35 mm; for a machine body weight of about 6 to 8 tons, h 1 is 22 mm and h 2 is 42 mm; for a machine body weight of about 10 to 13 tons, h 1 is 38 mm and h 2 is 58 mm; and for a machine body weight of 18 to 20 tons, h 1 is 40 mm and h 2 is 70 mm. Fig. 21 is a graph illustrating the relationship between machine body weight and rubber pad thicknesses (heights) h 2 showing durability of the crawler block rubber pad of the present invention. The hatched region in the drawing is a range in which durability was obtained for 50 or more hours in a running state. This figure illustrates that in a case in which the machine body weight is 16 tons, if the minimum pad depth h 2 is 40 mm, the durability standards can be met. Further, in cases of machine body weights of 4 tons or less, it is necessary to made the pad thickness at least 20 mm. The minimum value of the pad thickness is as illustrated by the data in Fig. 21. The maximum value is determined by the state in which the crawler is mounted to the main body and by the rigidity of the crawler itself. Hereinafter, further embodiments of the crawler block rubber pad of the present invention will be described in detail with reference to the drawings. Hereinafter, the crawler block 22 and the rubber pad 23 of one embodiment of the present invention will be described. Fig. 12 is a ground-contacting surface side plan view. Fig. 13 is a front view, and Fig. 14 is a side view. The rubber pad 23 is divided into rubber materials 23a, 23b to the left and the right at a thickness of 20 mm by the central recess 23' of the rubber pad 23. The surfaces of the rubber pads 23a, 23b are trapezoidal. In the present example, the lengthwise width p of the rubber pad 23 is 500 mm, the transverse width q is 165 mm, the height h 3 is 85 mm, and the transverse side width r is 140 mm. The link pitch P (unillustrated) at which the crawler blocks 22 are attached is 175 mm. Accordingly, in the present embodiment, F = 10 mm (F/P = 5.7%), G = 17 mm (G/P = 105). Next, an eleventh embodiment of the present invention will be described. In the present embodiment, the space F between the rubber materials 23 1 , 23 2 at both sides is less than or equal to zero. Namely, the rubber materials 23 1 , 23 2 always contact each other when the crawler is disposed horizontally. Fig. 15 is a side view of the crawler block 22 formed particularly favorably in the present embodiment, and Fig. 16 is a side view of a crawler using this crawler block 22. As illustrated in the figures, it is preferable that grooves 23 6 be formed in the rubber materials 23 1 , 23 2 along the longitudinal direction of the crawler block 22. By forming the grooves 23 6 , the rubber materials 23 1 , 23 2 formed at the end portions of the crawler block 22 can be easily bent by the contacting pressure when the rubber materials 23 1 , 23 2 contact each other. As a result, even if the space F between the rubber materials 23 1 , 23 2 is zero or less, i.e., the rubber materials 23 1 , 23 2 always contact each other, there is no particular hindrance. Namely, due to the grooves 23 6 , the rubber materials 23 1 , 23 2 bend easily so as to protrude toward the link 1 side, and the rubber materials 23 1 , 23 2 being easily abraded when they protrude in the opposite direction and contact the ground can be prevented. Cases in which the groove 23 6 is formed in only one of the rubber materials 23 1 , 23 2 can be contemplated. Still a further embodiment of the present invention will be described hereinafter. Fig. 17 is a plan view of an inner peripheral side portion of the crawler block rubber pad of the twelfth embodiment of the present invention. Fig. 18 is a plan view of an outer peripheral side portion, and Fig. 19 is a cross sectional view taken along line J-J of Fig. 17. In the figures, reference numeral 32 is a flat crawler block, 33 is a rubber pad, and 34 is a crawler link. As shown in the figures, the rubber pad 33 is formed at the inner surface periphery of the crawler block 32 in order to adhere the rubber pad 33 and the crawler block 32 together well and extend the life span of the crawler block rubber pad. If the rubber pads 33 protrude to the region where the crawler links 34 are connected to the crawler block 32, the attachment is unstable. Therefore, in the present embodiment, at the regions where the crawler links 34 are connected, the rubber pad 33 does not protrude at the inner peripheral side of the crawler block 32. In order to obtain this type of crawler block rubber pad, for example, as illustrated in Fig. 20, protrusions 41 are formed at the interior surface of a mold 40 for forming the crawler block rubber pad, so as to contact a region at which the crawler block 32 is set. In the present invention, because the reverse surface of the crawler block 32 is flat, bolt attachment holes 35 can be opened from either side, and the holes can be made to have a larger diameter at the crawler link side so that the fastening force can be improved. In the conventional crawler block with a grouser, the bolt attachment holes can only be formed from the grouser side. Therefore, the holes are tapered so as to become wide at the grouser side, and the fastening force is small. Further, because there are no grousers or the like at the ground-contacting surface, the thickness of the rubber pad can be made even larger. As a result, no local strain is applied to the rubber, and the durability of the rubber is improved. The rubber around the inner side of the crawler block 32 can be expected to improve durability as described above. It is preferable that the thickness M thereof is 4 mm or more. Alternatively, given that the width of the rubber at the transverse direction outer side of the crawler block 32 is K and that the width of the rubber positioned at the inner side is L, it is desirable that L is greater than or equal to 0.5K. This type of rubber at the inner side is also useful in preventing rusting of the crawler block 32. As illustrated in the figures, the four corners of the crawler block 32 are eliminated obliquely. This is to suppress wearing of the end portions of the pad rubber. However, the four corners may be eliminated such that the remaining surfaces are arc-shaped. Chamfering in the direction of thickness of the crawler block 32 or processing in cross sectional arc shapes are good means for achieving this object.

Claims: A rubber pad (13, 23, 33) of a crawler block (12, 22, 32) for a crawler having an inner pad surface vulcanized and adhered to outer side surfaces of said crawler block (12, 22, 32) and to inner side end surfaces thereof, a thickness (h 2 ) of a peripheral portion (13 2 , 13 3 , 13 4 ) of said rubber pad (13, 23, 33) along each longitudinal direction end and/or along each transverse directional end of said crawler block (12, 22, 32), which peripheral portion extends from a plane contacting said crawler block (12, 22, 32) to an outer side surface of said rubber pad (13, 23, 33), being greater than a thickness (h 1 ) of a central portion of said rubber pad (13, 23, 33), which central portion extends from the surface contacting said crawler block (12, 22, 32) to the outer side surface of said rubber pad (13, 23, 33). A rubber pad (13, 23, 33) according to claim 1, wherein the thickness (h 2 ) of said peripheral portion (13 2 , 13 3 , 13 4 ) of said rubber pad (13, 23, 33) is about 1 to 10 mm larger than the central thickness (h 1 ) of said central portion of said rubber pad (13, 23, 33). A rubber pad (13, 23, 33) according to claim 1, wherein the central thickness (h 1 ) of said central portion is at least 20 mm. A rubber pad (13, 23, 33) according to claim 1, wherein the thickness (h 2 ) of said peripheral portion satisfies the relation: PT ≥ 10 x (W) 0 ' 5 mm where PT is the peripheral thickness and W is a predetermined weight of a machine in tons having a crawler which comprises links (1) each having a rubber pad (13, 23, 33) according to claim 1, wherein the links (1) are connected by connecting members (6) to form an endless shape. A rubber pad (13, 23,33) according to claim 1, wherein the outer crawler surface is substantially planar. A rubber pad (13, 23, 33) according to claim 1, wherein the pad (13, 23,33), as viewed from a direction orthogonal to the outer pad surface, having a portion that extends away from an outer periphery of said crawler block (12, 22, 32) at a distance such that when said crawler block with the pad is arranged in an endless shape in a crawler, substantially no gap between said at least one crawler block (12, 22, 32) and an adjacent crawler block exists. A rubber pad (13, 23,33) according to claim 1, wherein the thicknesses (h 2 , h 1 ) of said peripheral portions and said central portion are set so as to allow a ground contacting surface of the rubber pad (13, 23,33) to be horizontal in a case in which the load of a machine body on which crawlers with rubber pads according to the preceding claims are arranged is applied to these rubber pads (13, 23,33). A crawler comprising links (1) connected together by connecting members (6) to form an endless shape such that the links (1) can be assembled onto a drive mechanism (7) of a machine having a predetermined machine body weight, each link (1) having an inner link surface facing the drive mechanism (7) of the machine when assembled thereon, and an outer link surface facing from the drive mechanism (7) when assembled thereon, each link having a crawler block (2; 12; 22; 32) with a rubber pad according to one of claims 1-7.

Inventors: KUMANO YOICHI, MURAMATSU TAKEO, KUMANO, YOICHI, MURAMATSU, TAKEO, Kumano, Yoichi, c/o Bridgestone Corporation
Applicants: BRIDGESTONE CORP, KOMATSU MFG CO LTD, BRIDGESTONE CORPORATION, KOMATSU LTD.
Application year: 1994
Main classification: B62D55
IPC codes: B62D55